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There are many different species of common house spider in the world.
They belong to the spider family Theridiidae, or
the cobweb weavers. Also known as
Combfooted Spiders, this family includes a number of well
known arachnids, including the American house spider, Achaearanea
tepidariorum, and the widow spiders Latrodectus spp.
Steatoda spiders are found throughout the world, in both temperate
and tropical climates. At least eight Steatoda spp. can be found
within the U.S. Steatoda spiders are small to moderately
small (3-9 mm) spiders with oval abdomens; they may be reddish, brownish
or black, with most species exhibiting a white band at the front of the
dorsal abdomen which may resemble a collar.
Steatoda spiders construct a strong, irregular web, somewhat
resembling the webs of widow spiders; this web is very sticky, making it
a highly effective snare for hobo spiders.
Steatoda grossa, the false black widow spider (pictured upper
left), is the most well known of the Steatoda spiders. Found in
cosmopolitan areas around the world, and on both coasts of the United
States, grossa is a larger (9 mm) Steatoda which, as its
common name suggests, may resemble a black widow spider (with no
hourglass). Specimens can be reddish to purplish brown in color, with
pale yellow markings on the dorsal abdomen, but many specimens are so
dark that these pale markings cannot be distinguished. Steatoda
grossa is a common and well known "house spider" in many areas,
constructing its webs in and around buildings, rock walls, and other
structures. It has long been known that the "false black widow" will
ensnare, kill and prey upon actual black widow spiders in its natural
habitat. Steatoda grossa has been observed to ensnare and prey
upon hobo spiders.
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Steatoda hespera |
Steatoda hespera, the western Steatoda
or western bud spider, is a smallish (7-8 mm), brown cobweb weaver that
is often misidentified as a small "brown" black widow: Pictured above
right, this species is common throughout the eastern half of the U.S.
range of the hobo spider. It now appears that this little arachnid may
be the single most effective predator of the hobo spider.
Steatoda triangulosa, the triangulate
 Steatoda,
or triangulate bud spider, pictured at left, is a cosmopolitan species
found in various areas of the world. This spider is moderately
small (5 mm), reddish to reddish-brown in color, and exhibits a well
defined pattern of light colored triangles on the dorsal abdomen.
This small household spider
is easily overlooked as it weaves cobwebs in the dark corners of houses,
basements, and outbuildings. The body is only about 1/8 to ¼ inch
long. The cephalothorax is brownish orange. Each segment of the yellow
legs is darker. This species is probably
native to Eurasia and has been introduced to North America relatively
recently. It is known from central and southern Europe, southern
Russia, the Mediterranean, St. Helena, and the United States. It is rare
in South America. In North America it is widespread and abundant
locally in and on houses. In both Europe and North America it lives in
houses in the northern part of its range and under stones and on walls
of buildings in the southern part of the range. It is
common in towns and cities, in and around man-made structures, in dark
corners of walls, lower angles of windows, and under eaves.
Like other comb-footed
spiders (family Theridiidae), these spiders build irregular webs and
suspend themselves from these snares while waiting for unsuspecting prey
to approach. Using a comb of serrated bristles on their hind legs they
enswathe their prey in sticky silk and wait for it to quiet before
approaching close enough to bite. Steatoda triangulosa is a frequent
associate of the brown recluse and the common house spider in closets
and crannies (Fitch 1963). It has been known to prey on many kinds of
arthropods, including ants, spiders (including the brown recluse),
ticks, and pillbugs. In Texas it has been known to prey on fire
ants and spiders inhabiting utility equipment housings.
Mating spiders and egg sacs have been found from late spring through
early fall . Egg sacs, about the size of the adult spider, are made of
loosely woven white silk, and about 30 eggs are visible inside each
sac.
Severe envenomation is
uncommon following the bite of Steatoda species, and there are no
known cases of human envenomation by S. triangulosa. When Steatoda
poisoning does occur, the neurotoxic symptoms are similar to those
resulting from black widow bites. The related species Steatoda
grossa, known as the false black widow or cupboard spider, has been
blamed for severe local and regional pain, nausea, and vomiting in
Australia. The symptoms, similar to those seen in latrodectism,
have been treated successfully with Latrodectus antivenom . In the United States,
S. grossa is confined to the
Gulf Coast and the West Coast . Fortunately, it appears
that this species does not occur in Arkansas. At least two species
of Steatoda have also been implicated in human envenomations in
Europe .
Another related species, S. borealis, is considered one of
the comb-footed spiders of most concern to urban pest controllers,
along with the black widow and common house spider. It is easily
distinguished from S. triangulosa by the dark colored abdomen with a
narrow, light colored median line. Although it is the most common
Steatoda of the eastern United States, it has never been found in
Arkansas and it is apparently rare south of Illinois, Iowa, and
Nebraska.
Information
and pictures were taken from children's projects and where credited to that
child does not claim to be original information. Where possible, permission
to reproduce has been sought. Any infringement of copyright is purely
unintentional.
Information
and pictures were taken from children's projects and where credited to that
child does not claim to be original information. Where possible, permission
to reproduce has been sought. Any infringement of copyright is purely
unintentional.
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